Drying plant and method of drying



2 Sheets-Sheet 1 I.IQN .I.

A I I I I I, I I ,I I

F. l. E. STENFORS Filed March 8, 1932 DRYING PLANT AND METHOD OF DRYING I I I I I I I March 26, 1935.

I\ lOl Patented Mar. 26, 1935 1,995,690 DRYING PLANT AND METHOD OFDRYING Frans Ivar Eugen Stenfors, Fredriksberg, Sundsvall, Sweden, assignor to Aktiebolaget Svenska Flaktfabriken, Stockholm, Sweden Application March 8, 1932, Serial No. 597,501 7 In Sweden March 11, 1931 5 Claims.

My invention relates to such drying devices in which drying takes place in a drying-plant which y a number of intermediate bottoms is divided into a number of canals for the goods to be dried, and the invention relates particularly to the arrangement that, with respect to the circulation, the drying canals are divided into groups each of which is connected to its special fan or fans so that the circulation in one group is independent of that in the other group.

By this arrangement it is possible to give the canals a considerable length relative to the height, and thus the drying plant will obtain a great capacity in relation to its size.

Further, by this arrangement, it is also possible to put the drying air in a very active and regular circulation in the whole plant which is very favourable for the drying. Thus, a high drying intensity is obtained at the same time that the drying becomes regular all over the'suriace of the goods to be dried. 1

Another advantage of this increased and improved circulation of the air is that therelative moisture of the drying air can be considerably in creased by maintaining the same drying intensity, the heat economy on the other hand being thus improved. When drying strip-shaped material such as a web, and particularly when it is the question of great capacities the device and method according to this invention are very important. The considerable length of the web of the goods or, generally speaking, the length of the way for the goods to be carried through the drying plant, and thus also the considerable length of the canals render the driving forward of the necessary quantity of circulation air difiicult. If, however, the present invention is applied to such cases a strong circulation of the air is easily obtained. The invention is particularly suitable where the canals are disposed in a known way in zigzag one above the other. The invention will be of a particularly great importance because this expedient must often be chosen due to reasons of space as the drying plant would otherwise have to be made inconveniently extensive, and therefore in all the embodiments of the invention described below the drying plant is constructed in such a way that the goods to be dried can be carried in zigzag through the plant.

Some embodiments of this invention are illustrated diagrammatically in the attached drawings in which Figures 1 and 2 are one embodiment.

Figures 3 and 4 a second embodiment, and

Figures '5 and 6 a third embodiment.

Figures 1 and 3 are vertical longitudinal sectionsthrough the above-mentioned embodiments. Figure 2 is a cross section IIII of Figure 1. Figure 4 is a cross section IV-IV of Figure 3. Figure 6 is a cross section VIVI of Figure 5.

In all the embodiments 1 indicates the drying plant, 2a, 2b the drying canals, 3 the fans, 4 the outlet openings of the plant, and 5 the inlet openings of the plant for the circulation air, i. e. the openings by which thedrying canals communicate with the fans. The suction chamber of each fan is indicated by 10, and the pressure chamber by 11. Further, 6 indicates inlets for fresh air, and 7 outlets for wet air. The dotand-dashed zigzag line 9 indicates strip-shaped goods to be dried, or, from a general point of view, the way. of said goods through the plant.

According to the invention the canals oi": the plant are obtained by disposing intermediate bottoms 8 in the plant, and the canals are connected to the fans in such a Way that, with respect to the circulation, the canals are divided into groups as mentioned above. In order to elucidate the principle of this invention reference is first made to Figures 1 and 2. Each group of canals comprises two canals 2a, 2b, and to each group belongs a fan 3. The canal 2a is connected to the suction chamber 10 'of the fan,and the canal 2b to the pressure chamber 11 of the fan. The two canals communicate with each other at the ends through. openings 22, obtained for instance by allowing the intermediate bottom 8 to end at some distance from the plant wall at both ends.

In Figures 1-6 the fans 3 arranged in one and the same vertical row have a common shaft 12 obtaining the driving power from any suitable source. The number of such fan aggregates may, of course, be varied according to the size of the plant. Thus, Figure 5 shows for instance four aggregates, viz two on each side.

By the difference of pressure in the canals 2a and 2b caused by the rotation of the fans the drying air is driven in. the direction of the arrows and passes from one canal to the other through the openings 22. Each group of canals 2a, 21) having its special fan group obtains a circulation independent of that of the other groups, due to the fact that the same quantity of air sucked from the canal 2a, is blown into the canal 2b. By introducing fresh air at 6 the quantity of air circulating in the lowest group of canals 2a, 2b obtains a surplus of air passing through the openings 22 over to the next group of canals et cetera which results therein that a corresponding quantity of wet air leaves, and that the desired renewal of the drying air is obtained. The same effect is, of course, obtained by removing wet air through the outlet '7. In this case a want of air will be the consequence in each over-lying group of canals relatively to the underlying one, said Want of air being compensated by introducing fresh air at 6.

The embodiment according to Figures 3 and 4 differs from those already described therein that one bottom 8 has its circulation opening 22 at the end of the plant, the next bottom its circulation opening 22 at the opposite end et cetera, so that in this case all the canals 2a and 2b form a through canal for the communication between the groups of the canals. In order to obtain a regular distribution of the air in the plant the inlet 6 and the outlet 7 are disposed each at its separate end of the drying canal formed by the canals 2a and 2b.

In the device comprising four fan aggregates shown in Figures 5 and 6 the fans on one side of the drying canals are disposed symmetrically to the fans on the opposite side, and thus the operation manner of the whole device will become the same as already described.

Other embodiments are possible within the scope of the invention and details in one embodiment may also be used in any of the shown embodiments.

It will be understood that the word web used in this specification does not only comprise continuous material such as a paper web, but also discontinuous material such as separate sheets of paper or the like fed through the plant along a path as described, so as to constitute, in effect, a continuous web.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A drying plant adapted to operate on webs of material comprising, a drying chamber, a plurality of intermediate partitions within said chamber, a plurality of canals for the passage of dryingair, each canal being bounded in part by one of said partitions and in part by a surface of the web to be dried, means for guiding the web between the partitions along a zigzag path with respect to the drying chamber, fan means located intermediate the ends of the canals, and means for causing the air propelled by said fan means to divide into two streams and to flow partly in the direction of travel of the web to be dried and partly in the opposite direction on both sides of each part of the web.

2. A drying plant adapted to operate on webs of material comprising, a drying chamber, a plurality of intermediate partitions within said chamber, a plurality of canals for the passage of drying air, each canal being bounded in part by one of said partitions and in part by a surface of the web to be dried, means for guiding the web between the partitions along a zigzag path with respect to the drying chamber, fan means located intermediate the ends of the canals, and means for causing the air propelled by said fan means to divide into two streams and to flow partly in the direction of travel of the web to be dried and partly in the opposite direction on both sides of each part of the web, each of said partitions having its ends spaced from the end walls of the drying chamber, whereby said canals are in communication with each other and with the air inlets and outlets of the drying plant.

3. A drying plant adapted to operate on webs of material comprising, a drying chamber, a plurality of intermediate partitions within said chamber, a plurality of canals for the passage of drying air, each canal being bounded in part by one of said partitions and in part by a surface of the web to be dried, means for guiding the web between the partitions along a zigzag path with respect to the drying chamber, fan means located intermediate the ends of the canals, and means for causing the air propelled by said fan means to divide into two streams and to flow partly in the direction of travel of the web to be dried and partly in the opposite direction on both sides of each part of the web, each group of canals comprising two pairs of canals coupled in parallel.

4. A drying plant adapted to operate on webs of material comprising, a drying chamber, a plurality of intermediate partitions within said I chamber, a plurality of canals for the passage of drying air, each canal being bounded in part by one of said partitions and in part by a surface of the web to be dried, means for guiding the web between the partitions along a zigzag path with respect to the drying chamber, fan means located intermediate the ends of the canals, and means for causing the air propelled by said fan means to divide into two streams and to flow partly in the direction of travel of the web to be dried and partly in the opposite direction on both sides of each part of the web, each group of canals comprising two pairs of canals coupled in parallel,

the fan means being located and operated to provide suction in each alternate pair of canals and to provide pressure in each other alternate pair of canals.

5. The method of drying webs of material which includes passing the material along a zigzag path through a drying chamber, adjacent parallel runs of the web being located in separate passages, supplying drying air at a point intermediate the ends of each alternate run of the web, withdrawing said drying air at a point intermediate the ends of each other alternate run of the web, causing the drying air to divide into two streams and to flow partly in the direction of travel of the web and partly in the opposite direction, the streams of air being so arranged that at any given point of the web the air on one surface of said web will flow in the same direction as the air on the other surface of said web.

FRANS IVAR EUGEN STENFORS. 

